Revised: September 2015
AN: 00675/2015
SUMMARY OF PRODUCT CHARACTERISTICS
1.
NAME OF THE VETERINARY MEDICINAL PRODUCT
Felimazole 2.5 mg coated tablets for cats
2.
QUALITATIVE AND QUANTITATIVE COMPOSITION
1 tablet contains:
Active substance:
Thiamazole
2.5 mg
Excipients:
Titanium Dioxide (E171)
1.12 mg
Erythrosine (E127)
Sodium methyl parahydroxybenzoate (E219)
0.01 mg
0.0034 mg
For the full list of excipients, see section 6.1.
3.
PHARMACEUTICAL FORM
Coated tablet.
Pink sugar-coated biconvex tablets, 5.5 mm diameter.
4.
CLINICAL PARTICULARS
4.1
Target species
Cats.
4.2
Indications for use, specifying the target species
For the stabilisation of hyperthyroidism in cats prior to surgical thyroidectomy.
For the long term treatment of feline hyperthyroidism.
4.3
Contraindications
Do not use in cats suffering from systemic disease such as primary liver disease or
diabetes mellitus.
Do not use in cats showing signs of autoimmune disease.
Do not use in animals with disorders of white blood cells, such as neutropenia and
lymphopenia.
Do not use in animals with platelet disorders and coagulopathies (particularly
thrombocytopenia).
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Do not use in cats with hypersensitivity to thiamazole or the excipient, polyethylene
glycol.
Do not use in pregnant or lactating females.
Please refer to section 4.7.
4.4
Special warnings for each target species
None.
4.5
Special precautions for use
Special precautions for use in animals
If more than 10 mg per day is required animals should be monitored particularly
carefully.
Use of the product in cats with renal dysfunction should be subject to careful risk:benefit
assessment by the clinician. Due to the effect thiamazole can have on reducing the
glomerular filtration rate, the effect of therapy on renal function should be monitored
closely as deterioration of an underlying condition may occur.
Haematology must be monitored due to risk of leucopenia or haemolytic anaemia.
Any animal that suddenly appears unwell during therapy, particularly if they are febrile,
should have a blood sample taken for routine haematology and biochemistry.
Neutropenic animals (neutrophil counts <2.5 x 109/l) should be treated with prophylactic
bactericidal antibacterial drugs and supportive therapy.
As thiamazole can cause haemoconcentration, cats should always have access to
drinking water.
Please refer to section 4.9 for monitoring instructions.
Special precautions to be taken by the person administering the veterinary medicinal
product to animals
Wash hands after use.
In the case of accidental ingestion, seek medical advice immediately and show the
package leaflet or the label to the physician.
Thiamazole may cause vomiting, epigastric distress, headache, fever, arthralgia,
pruritus and pancytopaenia. Treatment is symptomatic.
Wash hands with soap and water after handling litter used by treated animals.
Do not eat, drink or smoke while handling the tablet or used litter.
Do not handle this product if you are allergic to antithyroid products. If allergic
symptoms develop, such as a skin rash, swelling of the face, lips or eyes or difficulty in
breathing, you should seek medical attention immediately and show the package leaflet
or label to the doctor.
Do not break or crush tablets.
As thiamazole is a suspected human teratogen, women of child-bearing age and
pregnant women should wear gloves when handling litter of treated cats.
Pregnant women should wear gloves when handling the product.
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4.6
Adverse reactions (frequency and seriousness)
Adverse reactions have been reported following long term control of hyperthyroidism. In
many cases, signs may be mild and transitory and not a reason for withdrawal of
treatment. The more serious effects are mainly reversible when medication is stopped.
Adverse reactions are uncommon. The most common clinical side effects that are
reported include vomiting, inappetance/anorexia, lethargy, severe pruritus and
excoriations of the head and neck, bleeding diathesis and icterus associated with
hepatopathy, and haematological abnormalities (eosinophilia, lymphocytosis,
neutropenia, lymphopenia, slight leucopenia, agranulocytosis, thrombocytopenia or
haemolytic anaemia). These side effects resolve within 7-45 days after cessation of
thiamazole therapy.
Possible immunological side effects include anaemia, with rare side effects including
thrombocytopenia and serum anti-nuclear antibodies, and, very rarely,
lymphadenopathy. Treatment should be stopped immediately and alternative therapy
considered following a suitable period for recovery.
Following long term treatment with thiamazole in rodents, an increased risk of neoplasia
in the thyroid gland has been shown to occur, but no evidence is available in cats.
4.7
Use during pregnancy, lactation or lay
Laboratory studies in rats and mice have shown evidence of teratogenic and
embryotoxic effects of thiamazole. The safety of the product was not assessed in
pregnant or lactating cats. Do not use in pregnant or lactating females.
4.8
Interaction with other medicinal products and other forms of interaction
Concurrent treatment with phenobarbital may reduce the clinical efficacy of thiamazole.
Thiamazole is known to reduce the hepatic oxidation of benzimidazole wormers and
may lead to increases in their plasma concentrations when given concurrently.
Thiamazole is immunomodulatory, therefore this should be taken into account when
considering vaccination programmes.
4.9
Amounts to be administered and administration route
For oral administration only.
For the stabilisation of feline hyperthyroidism prior to surgical thyroidectomy and for the
long term treatment of feline hyperthyroidism, the recommended starting dose is 5 mg
per day.
Wherever possible, the total daily dose should be divided into two and administered
morning and evening. Tablets should not be split.
If, for reasons of compliance, once daily dosing with a 5 mg tablet is preferable, then
this is acceptable although the 2.5 mg tablet given twice daily may be more efficacious
in the short term. The 5 mg tablet is also suitable for cats requiring higher dose rates.
Haematology, biochemistry and serum total T4 should be assessed before initiating
treatment and after 3 weeks, 6 weeks, 10 weeks, 20 weeks, and thereafter every 3
months. At each of the recommended monitoring intervals, the dose should be titrated
to effect according to the total T4 and to clinical response to treatment. Dose
adjustments should be made in increments of 2.5 mg and the aim should be to achieve
the lowest possible dose rate.
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If more than 10 mg per day is required animals should be monitored particularly
carefully.
The dose administered should not exceed 20 mg/day.
For long term treatment of hyperthyroidism the animal should be treated for life.
4.10
Overdose (symptoms, emergency procedures, antidotes), if necessary
In tolerance studies in young healthy cats, the following dose-related clinical signs
occurred at doses of up to 30 mg/animal/day: anorexia, vomiting, lethargy, pruritus and
haematological and biochemical abnormalities such as neutropenia, lymphopenia,
reduced serum potassium and phosphorus levels, increased magnesium and creatinine
levels and the occurrence of anti-nuclear antibodies. At a dose of 30 mg/day some cats
showed signs of haemolytic anaemia and severe clinical deterioration. Some of these
signs may also occur in hyperthyroid cats treated at doses of up to 20 mg per day.
Excessive doses in hyperthyroid cats may result in signs of hypothyroidism. This is
however unlikely, as hypothyroidism is usually corrected by negative feedback
mechanisms. Please refer to Section 4.6 Adverse reactions.
If overdosage occurs, stop treatment and give symptomatic and supportive care.
4.11
Withdrawal period
Not applicable.
5.
PHARMACOLOGICAL PROPERTIES
Pharmacotherapeutic group: antithyroid preparations: sulphur-containing imidazole
derivatives.
ATCvet code: QH03BB02
5.1
Pharmacodynamic properties
Thiamazole acts by blocking the biosynthesis of thyroid hormone in vivo. The primary
action is to inhibit binding of iodide to the enzyme thyroid peroxidase, thereby
preventing the catalysed iodination of thyroglobulin and T 3 and T4 synthesis.
5.2
Pharmacokinetic particulars
Following oral dosing in healthy cats, thiamazole is rapidly and completely absorbed
with a bioavailability of >75%. However, there is a considerable variation between
animals. Elimination of the drug from cat plasma is rapid with a half-life of 3.5-4.0
hours. Peak plasma levels occur approximately 1-2 hours after dosing. Cmax is
approximately 0.8 µg/ml.
In rats thiamazole has been shown to be poorly bound to plasma protein (5%); 40%
was bound to red blood cells. The metabolism of thiamazole in cats has not been
investigated, however, in rats thiamazole is rapidly metabolised in the thyroid gland.
About 64% of the administered dose being eliminated in the urine and only 7.8%
excreted in faeces. This is in contrast with man where the liver is important for the
metabolic degradation of the compound. The drug residence time in the thyroid gland is
assumed to be longer than in the plasma.
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From man and rats it is known that the drug can cross the placenta and concentrates in
the foetal thyroid gland. There is also a high rate of transfer into breast milk.
6.
PHARMACEUTICAL PARTICULARS
6.1
List of excipients
Tablet core:
Lactose monohydrate
Povidone K30
Sodium starch glycolate
Magnesium stearate
Coating:
Sucrose
Povidone
Erythrosine
Macrogol 4000
Purified talc
White beeswax
Carnauba wax
Shellac
Titanium dioxide (E171)
Sodium methyl parahydroxybenzoate (E219)
6.2
Incompatibilities
Not applicable.
6.3
Shelf life
Shelf life of the veterinary medicinal product as packaged for sale: 3 years.
6.4
Special precautions for storage
Do not store above 25ºC.
Keep the container tightly closed in order to protect from moisture.
Keep the container in the outer carton.
6.5
Nature and contents of immediate packaging
White polypropylene tub with white low density polyethylene tamper evident lid
containing 100 tablets.
6.6
Special precautions for the disposal of unused veterinary medicinal
product or waste materials derived from the use of such products
Any unused veterinary medicinal product or waste materials derived from such
veterinary medicinal product should be disposed of in accordance with local
requirements.
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AN: 00675/2015
7.
MARKETING AUTHORISATION HOLDER
Dechra Limited
Snaygill Industrial Estate
Keighley Road
Skipton
North Yorkshire
BD23 2RW
8.
MARKETING AUTHORISATION NUMBER
Vm 10434/4050
9.
DATE OF FIRST AUTHORISATION
19 November 2004
10.
DATE OF ANY REVISION OF THE TEXT
September 2015
10 September 2015
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